Field of the Invention
The invention concerns a method for magnetic resonance imaging, a magnetic resonance apparatus and a computer-readable data storage medium.
Description of the Prior Art
In a magnetic resonance apparatus, also called a magnetic resonance tomography system, the body to be examined of an examination subject, in particular a patient, is conventionally exposed with the use of a basic field magnet to a relatively high basic magnetic field, for example of 1.5 or 3 or 7 tesla. In addition, gradient switching operations occur with a gradient coil unit. Radio-frequency pulses, in particular excitation pulses, are then emitted by a radio-frequency antenna unit via suitable antennas, and this leads to the nuclear spins (spins) of specific atoms excited in a resonant manner by these radio-frequency pulses being tilted by a defined flip angle with respect to the magnetic field lines of the basic magnetic field. When the spins are relaxed, radio-frequency signals, known as magnetic resonance signals, are emitted from the spins, and these are received by a suitable radio-frequency antenna, and then processed further. The desired image data can be reconstructed from the raw data acquired in this way.
For a specific scan a specific magnetic resonance sequence, also called a pulse sequence, should be emitted, which includes a series of radio-frequency pulses, in particular radio-frequency excitation pulses, and gradient switching operations, which are activated in appropriate coordination with the radio-frequency pulses along different gradient axes in different spatial directions. Readout windows that are appropriately timed are set, which specify the periods in which the induced magnetic resonance signals are detected.
An interference object may be present in an examination region of a magnetic resonance recording. This interference object is characterized by having a magnetic susceptibility that differs from the magnetic susceptibility of tissue surrounding the interference object. This interference object therefore can lead to magnetic interference fields that can make imaging of the interference object difficult and/or lead to image artifacts in the vicinity of the interference object.